I had the same problem, and in the end i found a screw that had come loose. I just removed it and the problem was solved. (need to remember to get a new one... ) The screw was holding the hinge to the actual window. I needed to open the window more than 180 degrees to get to the screw.
I hope this can help you and that it did not start raining yet.
Vebjørn Sundby, August 2009
